Persons with mobility impairments often depend on a wheelchair or walking aid to facilitate mobility. As a result, they are frequently subjected to physical barriers and obstacles, such as stairs and curbs. The Americans with Disabilities Act requires that these physical barriers be removed. To that end, ramps have been designed to provide some access; however, ramps can be very long and difficult to climb. Further, depending on the elevation change and available space, ramps may be impractical.
One solution is vertical lifts. Vertical lifts have been developed for use in a wide variety of settings including church pulpits, meeting chamber podiums, and courtrooms. Such a vertical lift includes a lift platform surrounded by vertical walls and one or more doors. Several linear actuators are encased within the walls and are driven by a single motor. Each linear actuator is rigidly attached to the lift platform via a wide, L-shaped connection bracket.
The above-described rigid connection between the lifting bracket and the lift platform can cause the vertical lift to bind during operation. Operating loads, such as the weight of a passenger or a wheelchair, can cause components of the vertical lift to deflect, potentially resulting in a binding condition. Similarly, manufacturing and installation tolerances can cause components to become misaligned, also resulting in a binding condition. Typical tolerances that could potentially result in such a misalignment include, but are not limited to, drive screw end nut run-out, drive screw and component straightness, floor flatness and levelness, and wall perpendicularity and squareness. Binding conditions cause high friction forces and dampen the operation of the machine, thus requiring increased power requirements for the motor. In addition, large and unsightly slots in the walls of the lift assembly are required for the wide brackets to extend from the linear actuators to the platform. Large and obtrusive covers are attached to the brackets to attempt to hide the slots.